The long-term objectiveb of this research are to understand developmental mechanisms that are involved during early neurogenesis, particularly those concerned with normal and abnormal closure of the neural tube, as well as with the ongoing processes of proliferation and cytodifferentiation that occur during this crucial period of development. Specific aims include immunocytochemical localization of neural cell adhesion molecules in dysraphic embryos, a quantitative analysis of neuraxial elongation, manipulation of neural tube elongation and closure in vitro, use of whole embryo culture to determine predictive parameters that are significant in producing the wide range of severity characteristic of lumbosacral dysraphism, and an ultrastructural cytochemical and immunofluorescence analysis of how dysraphism affects early commitment to neural cell lineages. This project will help to contribute to an understanding of the etiology Of specific human neurological disorders such as exencephaly, meningocele, anencephaly, and spina bifida.